22 September 2024
This past summer was my first time raising black swallowtail butterflies, from eggs to the final release. Having only raised monarchs until this point, I was feeling a little out of my element and didn’t have high hopes. I started by planting parsley, one of several host plants adult butterflies will lay their eggs on, and waiting patiently.
I wanted to document the process and my favorite pics here to reference next year, much like I did with my monarch post.
Unlike monarch caterpillars that will only eat milkweed, black swallowtail caterpillars live off many plants from the carrot family, such as Queen Anne’s lace, celery, parsley, carrots, dill, and parsnip. These are the plants an adult butterfly will consider a host plant in which to lay their eggs—much more flexible than monarchs.
In the spring, I planted six Italian and flat organic parsley plants in a raised planter on the patio and checked the leaves (tops and bottoms) often. I didn’t discover my first egg until August 2nd, after nearly giving up hope. After that though, there were new eggs each day for weeks. They didn’t all make it, which I’ll speak to more soon, but I stopped counting after collecting 65 eggs (just from the original six plants!). Each time I found one of these perfect pearl eggs, I’d cut the stem of the parsley and place in water within an enclosure so it could hatch safely.
Next year I am going to plant a variety of host plants to see which one proves to be their favorite.
Like the one I use for monarchs, I kept these in a fresh butterfly tent, always bought new or bleached to ensure there are no lingering spores or bacteria. I kept these enclosures on a screened-in patio for the summer, and they had a bottom lined with kraft paper for easy waste disposal.
While this setup has served me well for years, the lack of direct sunlight was possibly an issue this year. While I’m familiar with things like OE infections with monarchs and how best to combat it, I had never experienced “black death”. Towards the end of August, many of the caterpillars turned black and saggy and died. This was fairly widespread and devastating. After a bit of research and looking through images, it was clear this was an infection caused by bacteria that thrives in moist environments. So, it was an especially hot and humid summer and I had them living out of direct sunlight.
I bought a fresh enclosure, replaced all the existing parsley and waited. Caterpillars continued to get sick, but not quite as many and not as rapidly. I removed infected caterpillars and kept replacing their food often. It took weeks, but eventually they stopped getting sick and began making it to the chrysalis stage again. It was a really hard thing to witness. I felt terrible and was glad to be finally on the other side of things.
After this infection mayhem, I left a few eggs out on the planted, unprotected parsley to see if those caterpillars would have a better chance at survival. As it turns out, they did not. Once they reached their fourth instar stage, they disappeared. I have to assume they were eaten by one of the many types of birds that are in the yard at any given moment. So after this incident, I decided their odds were better back on the porch.
Continuing to feed them proved trickier than I originally expected. After all, I am at the grocery store constantly and there is lots of parsley there. The problem is that most of these herbs are treated, even if it says they’re not. After questionable parsley from a chain grocery store, I ended up only getting it from a local, organic market I trust. Even so, I continued to soak and rinse it thoroughly.
Once cleaned, I would pat dry, cut an inch off the end of the stems to enable better water absorption, and place in a fresh glass with water. I overfilled these to ensure there was plenty of dense surface area for the caterpillars to move around on without risk of falling in the water and to help them exit the parsley when they were ready to find the perfect spot to transform.
I observed some incredible things while caring for these caterpillars, such as their various stages (instars) where they look like a different species each time and the orange organ inside their head that inflates when they feel threated.
This stage was especially interesting to witness for the first time. Unlike monarchs, these black swallowtails attach themselves at two points and, over the course of a couple days, turn into these wild, alien-like shapes attached with a little hammock string.
I learned that the significant color variation happens as the season progresses, so early season chrysalises are bright green while later season ones are brown to best blend in with the changing foliage. They remain in this stage from one to two weeks, with mine definitely on the longer end of this range.
Now for the grand finale. Much like with monarchs, these butterflies need 4-6 hours to dry out once emerging from their chrysalises. There was even one instance over the summer where one emerged during a tornado (yes, really) so I kept it overnight, offering it fruit and it made it just fine until its release the following (much nicer) day.
As of this post, I have four chrysalises remaining and four caterpillars, which I have to assume will be over wintering on my porch at this point—see you in the spring, friends!
If you’d like to follow along with my bug photography adventure, I have a fun Pixelfed account for that—it’s one of my favorite things that I’ve gotten into.
